我在实验室准备做粗盐提纯的实验,其中过滤操作需要的仪器是( )
A.①③④⑥
B.①②③
C.②③④
D.④⑤⑥
答案:A
As is recorded in history, silkworms (蚕) were first raised by a woman in _____ is today Hebei Province.
A.where
B.the place
C.which
D.what
计量员根据计量仪器检定规程选择符合条件的国家法定机构,()进行送检。